Good Day!!!

I am using Shincarbon ST column( Catalog No #19808) for separation of permanent gases using TCD detector. I was able to elute H2,CO,CH4, CO2 gases without any problem( see attached figure 1).

However due to prolonged period of maintenance work in our lab GC(PerkinElmer Clarus 580)was offline for 1 month or so. Now when I try to elute these gases through column with same mentioned programme I dont observe any peaks(see attached chromatogram fig2)

I have crosscheck everything I could i.e 1) conditioning column 2)changing the column but still no peaks could be seen.What to do and how to solve this problem???